Xsbase 嵌入式设备驱动 Linux-2.4

用于xsbase linux-2.4

一．编辑文件

1）模块文件

#vi xsbase.c

#define    __NO_VERSION__

#include <linux/config.h>

#include <linux/module.h>

#include <linux/mm.h>

#include <linux/types.h>

#include <linux/fs.h>

#include <linux/errno.h>

#include <linux/init.h>

#include <asm/system.h>

#include <asm/uaccess.h>

static char      *data;

unsigned int xsbase_major = 0;

static int xsbase_open(struct inode *inode, struct file *file);

static int xsbase_release(struct inode *inode , struct file *file);

static ssize_t xsbase_read(struct file *file, char *buf, size_t count, loff_t *f_pos);

static ssize_t xsbase_write(struct file *file, const char * buffer, size_t count, loff_t *f_pos);

static struct file_operations chr_fops = {

       read:              xsbase_read,

       write:             xsbase_write,

       open:              xsbase_open,

       release:    xsbase_release,

};

static int xsbase_open(struct inode *inode, struct file *file){

       MOD_INC_USE_COUNT;

       printk("this chrdev is opened!\n");

       return 0;

}

static int xsbase_release(struct inode *inode, struct file *file){

       MOD_DEC_USE_COUNT;

       printk("this chrdev is released!\n");

       return 0;

}

static ssize_t xsbase_read(struct file *file, char *buf, size_t count, loff_t *f_pos){

       int    len;

       if (count < 0)

              return -EINVAL;

       len = strlen(data);  

       if (len < count)

              count = len;

       copy_to_user(buf, data, count+1);

       return count;

}

static ssize_t xsbase_write(struct file *file, const char * buffer, size_t count, loff_t *f_pos){

       if (count < 0)

              return -EINVAL;

       kfree(data);

       data = (char *)kmalloc(sizeof(char)*(count+1), GFP_KERNEL);

       if (!data)

              return -ENOMEM;

       copy_from_user(data, buffer, count+1);

       return count;

}

int init_module(void){

       int    res;

       res = register_chrdev(0, "xsbase", &chr_fops);

       if (res < 0){

              printk("can't get major name!\n");

              return res;

       }

       if(xsbase_major == 0)

              xsbase_major = res;

       return 0;

}

void cleanup_module(void){

       unregister_chrdev(xsbase_major, "xsbase");

}

2）测试文件

#vi test_xsbase.c

#include <stdio.h>

#include <sys/types.h>

#include <fcntl.h>

int

main(void)

{

       int    fd, length, rlen;

       int    i;

       char *buf = "hello, world!\n";

       char readbuf[12] = {0};

       fd = open ("/dev/xsbase", O_RDWR);

       if (fd <= 0){

              printf("Error opening device xsbase\n");

              exit(1);

       }

       length = write (fd, buf, strlen(buf));

       if (length < 0){

              printf("Error writting to device xsbase\n");

              exit(1);

       }

       rlen = read (fd, readbuf, 12);

       if (rlen < 0){

              printf("Error reading from device xsbase\n");

       }

       printf("the read result is %s\n", readbuf);

       close(fd);

       return 0;

}

二．编译

#arm-linux-gcc –c xsbase.c –I /…./2.4.18-rmk7-pxa1-XSBase255B/include –D__KERNEL__ -DMODULE          // 2.4.18-rmk7-pxa1-XSBase255B 内核文件

#arm-linux-gcc test_xsbase.c –o test_xsbase

三．下载

下载这两个文件到板子上有两种方法：Zmodem 和 ftp。

四．运行

#cd /root

#insmod –f xsbase.o

#vi /proc/devices                         // 可以看到xsbase 253

#mknod /dev/xsbase c 253 0        // major 253   minor 0

#./test_xsbase                             // 可以看到测试结果

#rmmod xsbase